Studies on the role of supercritical water in on-site upgrading system of bitumen by hydrothermal were carried out by varying experimental parameter such as reaction pressure, which influences the density of water. Experiments were carried out using a continuous flow reacting system operated under a temperature of 430 C. From the results such as the viscosity and the production of toluene insoluble and so forth, it was found that higher density supercritical water inhibits the pyrolysis of bitumen to lower molecular weight substance and the coking. Sato et al. found that the corking was inhibited because interactions among aromatic rings in quinoline could be disrupted. The dielectric constant of water in supercritical region is decreased to the same level of organic solvent. These interactions may be disrupted in the supercritical water. Accordingly, the supercritical water may easily exist around the hydrocarbons . As a result, this may prevent the bitumen from corking.
